The present disclosure relates to a developer case containing a toner and a carrier and an image forming apparatus including the developer case.
An electrographic image forming apparatus uses a development device to develop an electrostatic latent image formed on a surface of a photosensitive drum or the like. As such a developing manner, one manner using a one-component developer consisting of a toner and another manner using two-component developer consisting of the toner and a carrier are known.
In a case using the two-component developer, because the carrier composing the developer in the development device is sequentially deteriorated, there is a problem that lifetime of the development device is shortened. In order to cope such a problem, a manner (called as a “trickle development”) containing not only the toner, but also the carrier, in a developer case supplying the toner to the development device and supplying new carrier from the developer case to the development device at any time is known. By applying such a trickle development, the sequential deterioration of the carrier in the development device may be suppressed and prolongation of the lifetime of the development device may be actualized.
However, when the trickle development is applied, in order to intend to prevent unevenness of image density and to heighten image quality, it is important to stabilize a ratio (a mixture ratio) between the toner and carrier composing the two-component developer supplied from the developer case to the development device to the utmost. With regard to such a point, for example, in a manner filling the toner and carrier in turns to the developer case, even if the toner and carrier are agitated after the filling is completed, in a case where the agitation is insufficient, there is a possibility that the ratio between the toner and carrier composing the two-component developer supplied from the developer case to the development device becomes unstable. In addition, because the toner and carrier are filled to the same space in the developer case, if once the toner and carrier are filled to the developer case, the toner and carrier cannot be separated from each other and it is difficult to adjust again the ratio between the toner and carrier.
On the other hand, there is a configuration filling a premix toner, in which the toner and carrier are diffused in advance, to the developer case. However, in such a configuration, if the toner and carrier are not evenly diffused in the premix toner, similarly to the manner filling the toner and carrier in turns to the developer case, there is a possibility that the ratio between the toner and carrier composing the two-component developer supplied from the developer case to the development device becomes unstable.
By contrast, there is a configuration connecting a toner case and a carrier case, which are individually provided, via a tube to the development device. In this configuration, because the toner discharged from the toner case and the carrier discharged from the carrier case are mixed in the tube, the ratio between the toner and carrier composing the two-component developer supplied to the development device may become stable.
However, in this configuration, because the toner case and carrier case are individually provided, in addition to a drive source rotating rotation members (e.g. a conveying screw and an agitating paddle) provided in the toner case, another drive source rotating rotation members provided in the carrier case is needed, and accordingly, increase of manufacturing cost is caused. Moreover, because the toner case and carrier case are individually provided, a user must attach/detach individually the toner case and carrier case from the tube, and accordingly, working load of the user increases.